We propose to evaluate the clinical application of quantitative electrophysiology as offered commerically by Neurometrics, Inc. The service purports to provide "objective evaluation of brain function making it possible to determine the extent to which a patient's behavior problems may be related to abnormal brain function". The service is based on the research of E. Roy John and colleagues at the N.Y.U. Brain Research Laboratories. While the service is offered for any age and patient populaton, it has been developed primarily on school age children with learning problems and its applicability to this clinical group is the most advanced. We will evaluate the claims made and compare it with conventional assessement procedures on a very well specified population of reading retarded and normal children which we have already under study. Extensive neuro-physiological, psychometric, behavioral, and clinical data have already been collected on these children. We will also study a new, unscreened population of children, half who are enrolled in learning disabilities schools or clinics, and half from regular public school classrooms. We will address three sets of questions: 1. Sensitivity and specificity of Neurometrics. Can Neurometrics discriminate our dyslexic from our control population? Since our control group was also extensively screened, is the distribution of Neurometric values in our control group different from the Neurometric "normative" group" 2. Validation of functional interpretations. Can each of the functional interpretations. of regional abnormalities provided by Neurometrics be validated by psychometric tests, clinical-behavioral examination, or history? To what extent are these same defects found by more conventional assessments and missed by Neurometrics? 3. Comparison with UCSF battery. Do our active measures emphasizing EEG and ERP recording during active cognitive performance (e.g. reading, signal detection, selective attention) and assessment of sensorimotor integration add substantially ato what is detected by the passive Neurometrics test? This study will provide and unbiased, independent determination of whether the Neurometrics approach is truly ready for clinical application or whether it should still be considered a promising research effort.